1. Field of the Invention
The present invention relates to dobbies and other mechanisms for forming the shed on weaving looms, and it is directed more particularly to the drawing mechanisms of the connecting rod type which ensure coupling of the moveable actuation members of such a mechanism with the vertically displaceable heddle frames mounted on the loom.
2. History of the Related Art
In order to make matters clear, FIG. 1 of the accompanying drawings very schematically shows the general arrangement of a drawing mechanism of the type in question. In this FIGURE, reference 1a designates one of the actuation members of a dobby 1, while reference 2 corresponds to one of the heddle frames mounted on the weaving loom. It may be observed that, to ensure the articulated connection between the elements 1a and 2, the drawing mechanism includes at each frame 2, a series of connecting rods 3 oriented either horizontally or vertically, or obliquely, which are coupled to one another with the aid of oscillating levers 4 mounted side by side along fixed horizontal pins 40.
In the current technique as illustrated in FIGS. 2 and 3, each of the ends of each connecting rod 3 are in the form of a tube of flattened section which is cut out axially to form a terminal fork, between the flanges 3a of which is introduced a corresponding end of the oscillating lever 4. The pivoting assembly is operated with the aid of an intermediate ring or pivot 5 of circular profile, whose retention in an opening in the lever 4 is effected by a central rivet 6.
It should be noted here that such a structure creates a weakened zone, with the result that, having regard to the forces transmitted by the drawing mechanism, to the operational speeds imparted at the present time to the weaving mechanisms and to the difficulties of lubricating the assembly, ruptures frequently occur at the connecting rod/lever couplings. In addition, it will be noted that assembly by riveting opposes any dismantling, with the result that, in the event of a damaged coupling, it is necessary to replace a series of pieces.